1. Field of the Invention
This invention relates to a server unit, a server control method, and a recording medium which are for transmitting screen drawing data created at a server unit to a client unit to cause the client unit to display the data in a server-based computing (SBC) system.
2. Description of the Related Art
In a client-server system, there is a server-based computing (SBC) system which causes a desired application program to be started and run on the server unit by, for example, a remote operation on a client unit.
With the SBC system, screen drawing data for client display created by an application program of the server unit according to the operation input from the client unit is transmitted from the server unit to the client unit and displayed on the client unit each time the drawing is updated.
The SBC system has been designed on the assumption of a high-speed network without delay, such as an in-company local area network (LAN). However, if the amount of screen update data is large or the communication speed (bandwidth) of the network is low (narrow), it takes time for screen drawing data created by the server unit according to the operation input from the client unit to be transmitted to the client and displayed completely as one screen, which causes a poor response problem.
To improve the user's apparent response on the client unit, a screen transfer apparatus has been considered which transmits low-image-quality screen drawing data whose data amount is small and, after an interval, further transmits high-image-quality screen drawing data (e.g., refer to Jpn. Pat. Appln. KOKAI Publication No. 2006-246153).
Furthermore, in an environment where transmission delay is liable to occur because, for example, a wireless wide-area network (WAN) is used, there arises a problem: the response to the operation input from the client unit is impaired.